A conventional vending machine comprises a metal panel in its front, a displaying chamber, having a transparent front panel, which is arranged at an upper portion of the metal panel, and a conventional push button arranged on the transparent front panel.
The conventional push button comprises a case which is made from ASA (Acrylonitrile Styrene Acrylate) resin, a base which is combined with the case to form a frame for containing switch parts, and a flexible cover which is placed in the frame to provide a water-proof space. The case has oval openings for a plurality of lenses to be pushed by a customer and to display predetermined symbol and letters. When one of the lenses is pushed by a finger, a witch for selling an article is turned on.
The base has connectors on its back surface. Each of the connectors is connected to the control unit of the vending machine via a cable. The base is placed on the transparent front panel.
The lens is partially exposed through the oval opening formed in the case. The lens is in contact with a letter and symbol plate on its inside. Light is transmitted through letter and/or symbol portions of the letter and symbol plate, and shielded by the remaining portion of the letter and symbol plate. The flexible cover supports the letter and symbol plate on the opposite side of the lens. A reflector case which includes conical reflectors having apertures at the bottoms is placed on the inside of the flexible cover. The inclined plane of the reflector is processed to have a mirror surface.
A PCB (Printed Circuit Board) on which LEDs (Light Emitting Diodes) to radiate the letter and symbol plate through the acres of the reflectors for indicating "on sale" and "sold out" are mounted is placed on the base. A quantity of light which is supplied to the lens is increased, because the light emitted from the LEDs is reflected by the mirror surface of the reflector. Switching electrodes are also mounted on the PCB. Conductive members are mounted on the inside of the flexible cover to turn on and off the switching electrodes by pushing and releasing the lens.
A boss for fixing the push button on the transparent front panel is provided on the back surface of the base. An aperture into which a screw is inserted is formed in the center of the boss. Ring packings for avoiding water to invade into the displaying chamber are mounted on roots of the boss and the connector.
Each of the lenses is positioned to correspond to each of the article samples. When coins are inserted into the vending machine and there is not an article to be bought in the vending machine by a customer, the LED for indicating "sold out" is controlled to emit light The light from the LED is transmitted through the letter and symbol plate to be passed through the lens. Thus, the customer can know that the article is sold out
In the conventional push button for the vending machine, however, there are disadvantages in that its parts is large in number, and costs is high, because the provision of the letter and symbol plate is required to indicate "on sale" or "sold out", the lens can not be made small in width and length, because a predetermined indicating area and the quantity of light are needed for the letters of "sold out" and its size can not be small, because it needs the reflector case.